Real-world experience and clinical research converge in demonstrating that substance-abusers will continue to use drugs despite repeated adverse outcomes on physical and social well-being. This suggests that a characteristic of abuse may be a reduced ability to inhibit dysfunctional action patterns despite clear evidence of their maladaptivity (Paulus et al., 2002). Indeed, a growing body of behavioral, cognitive, electrophysiological and neuroimaging work suggests that cocaine abusers evidence core insensitivity to internally- and externally-generated signals of error. This insensitivity may reduce the ability to guide adaptive behavioral regulation, and may promote increased perseveration on dysfunctional action patterns, including repetitive drug-taking behavior and comorbid criminality. Despite this growing body of work, the nature of these error-monitoring deficits remains largely undifferentiated, however. Error-monitoring is composed of at least two potentially independent processes: an automatic error detection system that monitors for errors in goal-directed behavior and a less automatic system related to the conscious representation of that error. The majority of work evaluating error-monitoring in substance-dependent populations has focused on error-detection, and has reported consistent impairment. Little is currently understood regarding the state of subjective error-awareness in cocaine abusers, however, which precludes firm conclusions regarding the underlying nature of these error-monitoring deficits. Recent developments in electrophysiological and hemodynamic methods now afford the systematic isolation and evaluation of indices of automatic error-detection and conscious error-awareness, respectively. The present proposal seeks to build off these advances by collecting electrophysiological (EEG) and functional magnetic resonance imaging (fMRI) data within a sample of cocaine abusers (and matched controls), to characterize the integrity of neural circuits underlying their automatic and conscious components of error monitoring, respectively. The Mind Research Network has acquired a state-of-the-art mobile MRI scanner, deployed to various male and female correctional facilities, where epidimiological data indicates that over 65% of inmates suffer from serious substance abuse issues. The deployment of this mobile MRI system thus provides unprecedented access to a population of serious cocaine abusers with comorbid externalizing characteristics. With this access, we propose to collect multimodal (EEG/fMRI) data on 138 incarcerated participants, stratified into two groups: those who do (n = 69) and d not (n = 69) meet criteria for cocaine abuse. Participants will perform a time-estimation task that will afford a carefully controlled evaluation of the integrity of both automatic and concious components of error-monitoring within cocaine abusing individuals. In addition, we plan to follow-up our cocaine abusing participants at 1-year post-incarceration, to evaluate the extent to which error-monitoring integrity predicts future abstinence and relapse rates. The data obtained through this project will serve as the most comprehensive investigation of error monitoring abnormalities within a sample of serious cocaine abusers. The ultimate mission of The Mind Research Network is the development of novel treatment programs for serious psychological and mental disorders, and our group envisions the data collected fom this research as an important step towards future work focused on potential therepeutic and treatment applications.